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    <title>Document</title>
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    <script>
        //声明变量
        let a;
        let b, c, d;
        let e = 100;
        let f = 324, g = 'hasduias', h = [];

        //1.变量不能重复声明
        // let start = '扫扫扫';
        // let start = 'sadad';

        //2.块儿级作用域 全局，函数，eval
        //if else while for
        // {
        //     let girl = '周扬青';
        // }
        // console.log(girl);


        //3.不存在变量提升
        // console.log(song);
        // let song = '恋爱达人';


        //4.不影响作用域链
        {
            let school = '尚硅谷';
            function fn() {
                console.log(school);
            }
            fn();
        }




    </script>
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